[PATCH bpf-next 10/12] selftests/bpf: Add C tests for by-value arguments up to 16 bytes

[Yonghong Song <yonghong.song@linux.dev>]

Extend the by-value argument test with the aggregate cases, written in C
so that they depend on the compiler lowering the argument into a pair of
argument registers rather than on a hand-written register layout.

The programs cover a struct and a union that fill two registers, a
smaller struct that fills one, and two struct arguments in a row, each
with an int argument on either side so that a wrong slot count shows up
as a wrong value in the parameters around it, alongside the __int128
already there. A global function taking a struct with a pointer member
is rejected: the callee would receive the pointer as an opaque scalar.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 .../selftests/bpf/progs/verifier_int128_arg.c | 164 ++++++++++++++++++
 1 file changed, 164 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_int128_arg.c b/tools/testing/selftests/bpf/progs/verifier_int128_arg.c
index 044fc4a80055..b10fb4aeb405 100644
--- a/tools/testing/selftests/bpf/progs/verifier_int128_arg.c
+++ b/tools/testing/selftests/bpf/progs/verifier_int128_arg.c
@@ -7,6 +7,131 @@
 #define MIX_A	0xdeadbeefcafef00dULL
 #define MIX_B	0x0123456789abcdefULL
 
+struct pair {
+	__u64 lo;
+	__u64 hi;
+};
+
+struct small {
+	__u32 a;
+	__u32 b;
+};
+
+union upair {
+	__u64 halves[2];
+	struct {
+		__u64 lo;
+		__u64 hi;
+	} parts;
+};
+
+struct with_ptr {
+	void *p;
+	__u64 x;
+};
+
+static __noinline __u64 take_pair(int a, struct pair p, int c)
+{
+	return (__u64)a + p.lo + p.hi + c;
+}
+
+SEC("tc")
+__success __retval(0)
+int aggregate_arg_static_struct_c_test(struct __sk_buff *skb)
+{
+	__u64 a = skb->len ^ MIX_A;
+	__u64 b = skb->len ^ MIX_B;
+	struct pair p = { .lo = a, .hi = b };
+
+	if (take_pair(1, p, 2) != a + b + 3)
+		return 1;
+
+	return 0;
+}
+
+#if defined(__clang__)
+
+__noinline __u64 take_pair_global(int a, struct pair p, int c)
+{
+	return (__u64)a + p.lo + p.hi + c;
+}
+
+SEC("tc")
+__success __retval(0)
+int aggregate_arg_global_struct_c_test(struct __sk_buff *skb)
+{
+	__u64 a = skb->len ^ MIX_A;
+	__u64 b = skb->len ^ MIX_B;
+	struct pair p = { .lo = a, .hi = b };
+
+	if (take_pair_global(1, p, 2) != a + b + 3)
+		return 1;
+
+	return 0;
+}
+
+__noinline __u64 take_two_pairs_global(struct pair p, struct pair q)
+{
+	return p.lo + p.hi + q.lo + q.hi;
+}
+
+SEC("tc")
+__success __retval(0)
+int aggregate_arg_two_structs_c_test(struct __sk_buff *skb)
+{
+	__u64 a = skb->len ^ MIX_A;
+	__u64 b = skb->len ^ MIX_B;
+	struct pair p = { .lo = a, .hi = b };
+	struct pair q = { .lo = b, .hi = a };
+
+	if (take_two_pairs_global(p, q) != 2 * (a + b))
+		return 1;
+
+	return 0;
+}
+
+__noinline __u64 take_small_global(int a, struct small s, int c)
+{
+	return (__u64)a + s.a + s.b + c;
+}
+
+SEC("tc")
+__success __retval(0)
+int aggregate_arg_small_struct_c_test(struct __sk_buff *skb)
+{
+	__u32 a = skb->len ^ (__u32)MIX_A;
+	__u32 b = skb->len ^ (__u32)MIX_B;
+	struct small s = { .a = a, .b = b };
+
+	if (take_small_global(1, s, 2) != (__u64)a + b + 3)
+		return 1;
+
+	return 0;
+}
+
+__noinline __u64 take_upair_global(int a, union upair u, int c)
+{
+	return (__u64)a + u.parts.lo + u.parts.hi + c;
+}
+
+SEC("tc")
+__success __retval(0)
+int aggregate_arg_union_c_test(struct __sk_buff *skb)
+{
+	__u64 a = skb->len ^ MIX_A;
+	__u64 b = skb->len ^ MIX_B;
+	union upair u;
+
+	u.halves[0] = a;
+	u.halves[1] = b;
+	if (take_upair_global(1, u, 2) != a + b + 3)
+		return 1;
+
+	return 0;
+}
+
+#endif
+
 typedef unsigned __int128 u128;
 
 __noinline __u64 take_i128_global(int a, u128 v, int c)
@@ -28,4 +153,43 @@ int aggregate_arg_int128_c_test(struct __sk_buff *skb)
 	return 0;
 }
 
+#if defined(__BPF_FEATURE_STACK_ARGUMENT)
+
+static __noinline __u64 take_spilled_pair(int a, int b, int c, int d, struct pair p)
+{
+	return (__u64)a + b + c + d + p.lo + p.hi;
+}
+
+SEC("tc")
+__arch_x86_64 __arch_arm64
+__success __retval(0)
+int aggregate_arg_spilled_struct_c_test(struct __sk_buff *skb)
+{
+	__u64 a = skb->len ^ MIX_A;
+	__u64 b = skb->len ^ MIX_B;
+	struct pair p = { .lo = a, .hi = b };
+	int n = skb->len;
+
+	if (take_spilled_pair(n, n + 1, n + 2, n + 3, p) != a + b + 4 * n + 6)
+		return 1;
+
+	return 0;
+}
+
+#endif
+
+__noinline __u64 take_with_ptr_global(struct with_ptr s)
+{
+	return s.x;
+}
+
+SEC("tc")
+__failure __msg("type STRUCT in take_with_ptr_global() is not composed of scalars")
+int aggregate_arg_ptr_member_fail(struct __sk_buff *skb)
+{
+	struct with_ptr s = { .p = skb, .x = skb->len };
+
+	return take_with_ptr_global(s);
+}
+
 char _license[] SEC("license") = "GPL";
-- 
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